Microturbines
Situation
The old axiom “Waste not, want not” holds especially true for the City of Sheboygan. We have more biogas – a by-product of the wastewater treatment process – then we know what to do with. Some of the biogas is used to fuel boilers which heat the digesters and a Caterpillar engine that drives an influent pump. However most is not used.
When a boiler upgrade was planned, it seemed the perfect time to consider other uses for the excess gas. “With energy costs increasing each year, we were actively looking at different ways to reduce our total energy bill,” said Dale Doerr, Plant Superintendent.
Through research, plant personnel learned that microturbines were ideally
suited to utilize the biogas as fuel to produce electricity and heat without the
noise, vibration and maintenance issues of reciprocating engines.
Solution
Alliant Energy -Wisconsin Power and Light Company (WP&L), a distributor of CapstoneTM MicroTurbines, provided the answer. A team from WP&L and the City of Sheboygan was assembled to develop the optimal solution. The result was a ten-Capstone installation capable of generating 300 kW of electrical power and recovering one million BTU of heat per hour.
The Capstones, the heat exchangers and the gas conditioning equipment are owned by WP&L but are located at the City’s wastewater treatment plant. The biogas fuel is provided by the city, the electricity produced is sold by WP&L to the city and the heat is used by the city to maintain the proper temperature in the digesters.
Result
The overall result is a significant energy savings for the City of Sheboygan
and the use of a renewal-energy source to provide electricity which would
otherwise need to be generated at the coal-fueled power plant nearby. “Our
partnership with Alliant Energy made this project a reality,” Doerr said.
Installations
“With energy costs increasing each year, we were actively looking at different ways to reduce our total energy cost. Since we were wasting excess biogas produced at the wastewater treatment plant, it became evident that we could use the excess biogas as fuel for the Capstone MicroTurbines and reduce our energy cost. Our partnership with Alliant Energy made this project a reality.”